Althusser is a structuralist Marxist. This should make you ask,
how can that be? How can you combine Marxism, which relies on social/historical
analysis, with structuralism, which relies on ahistorical/asocial analysis?
Althusser answers that initially with distinction between ideologies
(historical/social) and ideology (structural).

This essay as it appears in Critical Theory Since 1965 is an excerpt from a
longer piece discussing the relation between the State and subjects. Althusser
is asking why subjects are obedient, why people follow the laws, and why isn't
there a revolt/revolution against capitalism. His view of ideology and
ideologies comes out of his understanding of the relations between State and
subject (between government and citizens), so it's worth while to examine those
ideas for a minute.

The State, for Althusser, is the kind of governmental formation that arises with
capitalism; a state (and you can substitute the word "nation" here to help
conceptualize what the "State" is) is determined by the capitalist mode of
production and formed to protect its interests. It is historically true (whether
you are a Marxist or not) that the idea of nations as discrete units is
coterminous with capitalism. It is also possible that democracy, as an ideology
and/or a governmental form is also coterminous with capitalism, as democracy
gives the "illusion" that all people are equal, and have equal power (and hence
masks relations of economic exploitation).

Althusser mentions two major mechanisms for insuring that people within a State
behave according to the rules of that State, even when it's not in their best
interests (in regards to their class positions) to do so. The first is what
Althusser calls the RSA, or Repressive State Apparatuses, that can enforce
behavior directly, such as the police, and the criminal justice and prison
system. Through these "apparatuses" the state has the power to force you
physically to behave. More importantly for literary studies, however, are the
second mechanism Althusser investigates, which he calls ISAs, or Ideological
State Apparatuses. These are institutions which generate ideologies which we as
individuals (and groups) then internalize, and act in accordance with. These
ISAs include schools, religions, the family, legal systems, politics, arts,
sports, etc. (as listed in the footnote on p.239). These organizations generate
systems of ideas and values, which we as individuals believe (or don't believe);
this is what Althusser examines. How do we come to internalize, to believe, the
ideologies that these ISAs create, (and thus misrecognize or misrepresent
ourselves as unalienated subjects in capitalism)

Althusser's answer starts with the distinction between
ideologies and ideology. IDEOLOGIES are specific, historical, and differing; we
can talk about various ideologies, such as Christian ideology, democratic
ideology, feminist ideology, Marxist ideology, etc. IDEOLOGY, however, is
STRUCTURAL. Althusser says that ideology is a structure, and as such is
"eternal," i.e. to be studied synchronically; this is why Althusser says (on p.
240) that ideology has no history. He derives this idea of ideology as a
structure from the Marxist idea that ideology is part of the superstructure, but
he links the structure of ideology to the idea of the unconscious, from Freud
and from Lacan.

Because ideology is a structure, its contents will vary, you can
fill it up with anything, but its form, like the structure of the unconscious,
is always the same. And ideology works "unconsciously." Like language, ideology
is a structure/system which we inhabit, which speaks us, but which gives us the
illusion that we're in charge, that we freely chose to believe the things we
believe, and that we can find lots of reasons why we believe those things.

Althusser's first premise or thesis (p. 241a, in italics) is that "Ideology is a
'representation' of the Imaginary Relationship of Individuals to their Real
conditions of existence." He begins his explanation of this pronouncement by
looking at why people need this imaginary relation to real conditions of
existence. Why not just understand the real?(p. 241b).

The first answer to this question, Althusser says, comes from the 18th century,
and the idea that ideology comes from priests and despots. This is basically a
conspiracy theory, which says that a handful of powerful men fooled the populace
into believing these (falsified) representations/ideas about the world. (This is
the eighteenth-century version of what I've said about feminism: that the men
all got together one day and invented sexism, and the women were fooled by it).

The second (and, from the Marxist perspective, the correct) answer is that the
material alienation of real conditions predisposes people to form
representations which distance (alienate) them from these real conditions. In
other words, the material relations of capitalist production are themselves
alienating, but people can't quite deal with the harsh reality of this, so they
make up stories about how the relations of production aren't so bad; these
stories, or representations, then alienate them further from the real
(alienating) conditions. The double distancing involved here, or the alienation
of alienation, works like an analgesic, a pill, to keep us from feeling pain of
alienation; if we didn't have these stories, we'd know the alienation of the
real relations of production, and we'd probably revolt--or go nuts.

These ideas about representation and reality assume that what is reflected in
the imaginary representation of the world found in ideology is the "real world,"
or real conditions of existence. Althusser says that ideology doesn't represent
the real world per se, but human beings' RELATION to that real world, to their
perceptions of the real conditions of existence. In fact, we probably can't know
the real world directly; what we know are always representations of that world,
or representations of our relation to that world. Ideology then is the imaginary
version, the represented version, the stories we tell ourselves about our
relation to the real world.

So the "real world" becomes, not something that is objectively out there, but
something that is the product of our relations to it, and of the ideological
representations we make of it--the stories we tell ourselves about what is real
become what is real. That's how ideology operates.

In more Marxist terms, what ideology does is present people with representations
of their relations to relations of production, rather than with representations
of the relations of production themselves.

Marxism originally formulated ideology as an illusionary representation of the
relations of people to real conditions. For example: my real condition, as a
professor, is that of a "cultural worker," someone paid to perform intellectual
labor in teaching. My salary is not nearly as large as that of a doctor, lawyer,
movie star, or athlete (not even in minor league baseball!!). What might be
considered my "exploitation," or my "real" economic conditions, are "masked"
with an ideology--that teaching and being a college professor is of high
moral/social value, if not of high economic value, that the rewards of teaching
are immaterial, that I get social status and respect (instead of money) for
being the repository of knowledge, etc.

That's one notion of ideology: it keeps me happy, thinking
that I am really an important person, when the real conditions of my
economic existence show how relatively unimportant I am. I buy into that
ideology (that being a professor is important), and am therefore willing to
tolerate my exploitation (and my alienation from the products of my own
mental labor, i.e. the surplus intellectual value I create in you) by
believing that I get "other" rewards besides money for doing this job.

Althusser says, by contrast, that my ideology is an illusion,
but it's an illusion, or an imaginary understanding, not of the relations of
production themselves, but of my relation to them. Thus I think I'm cool because
I'm not working in a factory, and I think I'm smarter than factory workers
because I assume that factory workers aren't very bright, or they wouldn't be
working in factories.

The relations of production here are in assuming that factory
workers lack education (that relations of production have structured a
relationship between job and education); my relation to that relation of
production is to feel superior to it. That's what Althusser says is ideology.
Althusser's Thesis II appears on p. 242b: "Ideology has a material existence."

It's important for Marxists always to be grounding their
analysis in material practices, material relations (since Marxism is, after all,
grounded in dialectical materialism)--so if we want to talk about IDEAS, we need
to be able to talk about them as MATERIAL (so that we don't lapse into idealism,
or an argument that ideas are more "real" than material objects).

So, what Althusser does to assert that ideology is material is
to say that ideology always exists in two places--in an apparatus or practice
(such as a ritual, or other forms of behavior dictated by the specific ideology)
and in a subject, in a person--who is, by definition, material. Note the
insistence on the material in the italicized quote on 243.

On p. 244, Althusser says that ideology, as material practice, depends on the
notion of the subject. Hence the two theses on 244: "there is no practice except
by and in an ideology" and "there is no ideology except by the subject and for
subjects". In short, there are no belief systems, and no practices determined by
those belief systems, unless there is someone believing in them and acting on
those beliefs.

Hence the final part of Althusser's argument: How is it that individual subjects
are constituted in ideological structures? Or, in other words, how does ideology
create a notion of self or subject?

All ideology has the function of constituting concrete individuals as
subjects--of enlisting them in any belief system, according to Althusser. That's
the main thing ideology as structure and ideologies as specific belief systems
do--get people (subjects) to believe in them. There are three main points that
Althusser makes about this process of becoming subjects-in-ideology.

1. We are born into subject-hood--if only because we're
named before we're born; hence we're always-already subjects.

2. We are always-already subjects in ideology, in specific ideologies, which
we inhabit, and which we recognize only as truth or obviousness. Everybody
else's beliefs are recognizable as ideological, i.e. imaginary/illusory,
whereas ours are simply true. Think, for example, about different religious
beliefs. Everybody who believes in their religion thinks their religion is
true, and everyone else's is just illusion, or ideology.

3. How does ideology (as structure) get us to become subjects, and hence not
to recognize our subject positions within any particular ideological
formation? How do we come to believe that our beliefs are simply true, not
relative? Althusser answers this on 245b with the notion of INTERPELLATION.
Ideology INTERPELLATES individuals as subjects. The word "interpellation"
comes from the same root as the word "appellation," which means a name; it's
not the same as the mathematical idea of "interpolation." Interpellation is
a hailing, according to Althusser. A particular ideology says, in effect,
HEY YOU--and we respond ME? You mean me?? And the ideology says, yes, I mean
you.

You can see examples of this every day in commercials. I saw one
the other night for a home gym system, claiming that "this machine will give you
the kind of workout you desire, meeting your needs better than any other home
gym." Each instance of "you" in that ad was an interpellation--the ad seeming to
address ME PERSONALLY (in order to get me to see myself as the "you" being
addressed, and hence to become a subject within its little ideological
structure). This is also what Mr. Rogers does, when he looks sincerely into the
camera and says "yes, I mean you." It also happens in the Uncle Sam recruiting
posters which say "I want YOU for the Army."

Althusser makes some final points about ideology working this way to "hail" us
as subjects, so that we think these ideas are individually addressed to us, and
hence are true. He says that ideology, as structure, requires not only subject
but Subject. In using the capital S, he invokes an idea similar to that of Lacan
(whom Althusser studied and wrote about), that there is a small-s subject, the
individual person, and a capital S Subject, which is the structural possibility
of subjecthood (which individuals fill). The idea of subject and Subject also
suggests the duality of being a subject, where one is both the subject OF
language/ideology (as in being the subject of a sentence) and subject TO
ideology, having to obey its rules/laws, and behave as that ideology dictates.

The interpellated subject in the ideology of the home gym commercial would thus
order the gym, behave as if bodybuilding or rigorous exercise was a necessity,
something of central importance. The Subject here would be some notion of
physical perfection, or body cult, the rules that the subject is subjected to.
Althusser uses the example of Christian religious ideology, with God as the
ultimate Subject--the center of the system/structure.

On p. 248 Althusser links his ideas about ideology to Lacan directly, noting
that the structure of ideology is specular (like Lacan's Imaginary, like the
mirror stage).

There are a couple of things worth noting about Althusser as a "bricoleur" of
other theorists. Althusser was enchanted by Freud, and even more enchanted by
Lacan; the ideas of the imaginary, the mirror, the specular, and the
subject/Subject are all gotten from or parallel to Lacanian notions. Also, as a
Marxist, Althusser privileges SCIENCE as a form of knowing that is outside of
any ideological structure, a type of knowledge that really IS simply true,
because objective and material--hence his comment on 246 that the only way to
know when ideology is ideological is through scientific knowledge.

Is this theory useful to literature? Yes, because it enables us to talk about
how a literary text, as a subset or transformation or production of ideology (or
of specific ideological formations) also constitutes us as subjects, and speaks
to us directly. The most obvious form of how a literary text might interpellate
us as subjects is one that uses direct address, when the text says "dear reader"
(as Uncle Tom's Cabin does with annoying frequency). All texts interpellate
readers by some mechanism, in some ways; all texts create subject positions for
readers, whether that construction of subject positions is obvious or not. We
will look at this idea of subject positions within literary texts further with
Foucault.